Counterbalanced door construction



Jan. 5, 1954 J McKEE ET AL 2,664,597

COUNTERBALANCED DOORv CONSTRUCTION Filed July 31, 1952 2' Sheets-Sheet l Inventor's John. E mcKee meluin BHarBler v Gigs.

7 Jan. 5, 1954 J. F. M KEE ET AL COUNTERBALANCED DOOR CONSTRUCTION 2 Sheets-Sheet 2 Filed July 51, 1952 Inventors John F. mcKee male/in E. Hart let 1 3; W, Moi/f Patented Jan. 5, 1954 COUNTERBALANCED DOOR CONSTRUCTION John F. McKee, Aurora, and Melvin E. Hartzler, Downers Grove, 111., assi'gnors to McKee Door Company, Aurora, 111., a corporation of Illinois Application July 31, 1952', Serial No. 301,946

3 Claims.

The present invention relates to counterbalanced door constructions and more particularly is concerned with a construction for a building having a comparatively wide and high door opening such as an airplane hangar.

Aircraft hangars and similar type buildings are characterized by the fact that they provide a large enclosed space having a door opening which extends the major portion of the height of the building and which usually is as long as the building. It is customary to provide such doors in several sections which roll horizontally upon either top or top and bottom tracks into position beyond the ends of the hangar. In more elaborate installations the door may be provided in sections which roll upwardly so as to clear the door space.

Since hangar doors are necessarily large in proportion to the size of the buildings, and since normally the major portion of the weight of the doors is carried by the building structure, it is apparent that since the building must be designed and constructed to carry the door weight, it is therefore more expensive than it would be if the door were self-supporting. The present invention overcomes this and other objections to conventional practice and provides a door which can be used in a single piece and which because of its construction is admirably suited to stand wind loads, and to withstand its own weight Without objectionable distortion in any position. Further, the door is provided with an arrangement such that it is supported upon its end foundation and in fact touches the hangar structure only when in a completely down position at which point a sealing joint upon the door engages a portion of the door or jamb so as to prevent leakage.

This application is a division of our copendingapplication Serial No. 669,078 filed May 11, 1946, entitled Airplane Hangar Door, now Patent No. 2,610,366.

A primary object of the invention claimed in this divisional application is to provide a. new and improved counterbalanced door structure wherein the door is perfectly counterbalanced in all positions.

Another object of our invention is to provide a counterbalanced door structure whereby a large door of the kind suitable for an air plane hangar can be quickly and easily operated by either-manually or power operated means.

Another object of our invention is to provide a new and improved counterbalanced door structure of simple and inexpensive construction.

Other objects and advantages will become apparent as the description proceeds,

In the drawings:

Fig. 1 is a front quarter perspective view of a hangar building embodying the present invention. In this view the door is shown in closed position.

Fig. 2 is an end view of one form of door and counter-balancing mechanism therefor.

Fig. 3 is a similar view of a modification showing the door in closed position; and

Fig. 4 is a view of the embodiment of Fig.3 but showing the door in open position.

In Fig. 1 of the drawings we have shown a perspective view of a hangar which is substantially semicylindrical in shape. Preferably it is formed of structural steel shapes cut and welded together to form prefabricated trusses in an appropriate and well-known manner and then is covered with sheet metal to form a tight enclosure. As seen in Fig. 1, the ends of the building are indicated generally by the numeral 10 while the curved wall which forms the back, roof, and portion of the front wall is indicated by the numeral 12. If desired, ofiice or shop space may be partitioned off at one or two corners of the building at the back and provided with a separate entrance [4. This is particularly advantageous if the building is of such size that the aircraft to be housed therein do not occupy substantially the full internal space.

At the front of the building a large generally rectangular opening 16 is provided through which aircraft can be moved from the interior to the exterior thereof. This opening is closed by an overhead-type door !8 which has slightly less radius of curvature thanthe face of the building and is set back slightly so that it can move into an overhead position inside of the building while clearing the building roof and trussing which supports the latter. For the convenience of the users the large door 18 may be provided with a small entrance door 20 which is recessed slightly beyond the surface of the large door and which slides to one side on top and bottom tracks (not shown).

The building, with the exception of the door, may be largely conventional in construction but may be made of lighter than normal construction in that the door is separately supported and the building therefore does not have to carry the weight of the door. Inasmuch as the invention claimed herein is not primarily concerned with the structure of the hangar building per se, but rather with the door and its counterbalancing mechanism, a detailed description of the building proper is deemed to be umiecessary for the present purpose.

The door l8 may be made in various ways, and in Fig. 2 is shown as comprising a sheet metal front wall 26 which is secured to and supported by internal trussing formed of longitudinally extending stringers 30 which support vertical ribs 32. This structure is in turn braced by diagonally extending members 34 and as thus constructed is sufficiently strong with comparatively little internal trussing. At any rate it is one of the features of the present invention to provide a door of this type which is sufficiently strong so that it may be supported at the ends alone and when thus supported will resist any anticipated wind load and will avoid troublesome flexure when supported by the ends in different positions.

This door is located substantially immediately inside the door opening. The end walls It of the buildings support inwardly extending jambs 36 which are curved so as to fit the front face of the convex door. At its ends the door covering 26 may be provided with jamb strips of rubber, canvas, or similar material which presses against the jamb 36 so as to seal the door against leakage. Preferably these jamb strips should be located directly opposite the end door frame members which are similar in shape to the ribs 32 so as not to stress the sheet metal door covering.

Each end of the door frame is connected to upper and lower rearwardly extending door supporting arms 36 and 38 respectively which together form a triangular yoke braced by a diagonal member 46. At the apex where these two members are brought together they are secured in rigid relationship by being welded or otherwise secured to gusset plates 42 or other suitable structural elements. A bearin is associated with the gusset plate 42 at each end of the door and this bearing which has its axis parallel to the face of the door is journaled upon a horizontal pin or bolt 44 secured to the upper end of a triangular standard 46. The standards 46 are formed of inner and outer structural members which straddle the yoke 36, 38 and support the bearing pins 50 at each end of the door. The lower end of each standard is secured to bolts or threaded reinforcing rods whose other ends are fixed within the top of a concrete pier or foundation member 48.

The door may be swung about the pins 50 into a position above the door opening and underlying the roof of the hangar as indicated in dot and dash lines in Fig. 2. Under these conditions the weight of the door is carried entirely by the pins 50 and upon the separate piers or foundation members 48 which form no portion of the structure of the hangar building proper. Under no conditions therefore does the door place any load upon the building. Preferably, so as to keep as large a free space within the hangar as possible, the piers 48 are located immediately adjacent the end walls of the hangar.

Inasmuch as a door of the size necessary in buildings of this character is comparatively heavy, a feature of our invention is the provision of a counterbalancing system so effective that for all practical purposes the only energy necessary to be expended in opening the door consists merely in that necessary to overcome friction. This counterbalancing system has been found to be effective throughout the entire range of operation of the door to a degree such that the door will remain in any set position. It has been found practical therefore to provide a simple manually operated crank door opener for moving hangar doors of this type in even, comparatively large sizes. Of course, if desired, motor driven door openers may be used and will be preferable for very large doors.

The counterbalancing system comprises a curved cam-like track 56 which is rigidly secured to the upper arm 38 and braced by a strut 52 attached to the door frame. A cable 54 lies over the face of this track 50 and has one end secured to the lower end 56 of the track in any suitable manner. With the door in closed position the shape of the track is such that the cable extends from the point of attachment 6!! in a direction forwardly and upwardly and gradually curves around until it is extending in a direction upwardly and backwardly. From the end of the cam-like track 56 the cable 54 extends rearwardly and upwardly in the hangar and passes over one or more pulleys 66 located centrally in the hangar from front to back. From the pulley or pulleys 64 the cable extends backwardly and is secured to a counterweight 58. The pulleys 64 may be secured to the hangar building itself or, if desired, separate posts may be provided entirely independent of the building proper for the purpose of carrying the counterweight pulleys.

In Figs. 3 and 4 we have shown a modification using a slightly different construction of camlike track 56 but which operates on the same principle as the construction of the previous embodiment. Figure 3 shows the door in closed position whereas Fig. 4 shows the door in open position. As best seen in these Figures 3 and 4 the cam track 56 is so formed that the distance A times the weight of the door equals the distanoe B times the weight of the counterweights in all positions of the door when A is the horizontal distance between the center of gravity indicated at X of the door system and the pivot point 44 and B is the shortest distance from the pivot point to the line C which is an extension of the line of the cable passing from the cam track 50' to the pulley 56. With this arrangement the weight of the counterweights 58 can be selected to substantially exactly balance the weight of the door in one position, with the result that the door will be balanced in all positions.

This balancing of the door in all positions results from the fact that the curvature of the camlike tracks 50 and 50 is such that for all positions of the door the distance B varies so that in each position this distance times the total weight of the counterweights is equal to the weight of the door times the distance A which also varies, as clearly shown by a comparison of Figs. 3 and 4. It is only where this relationship exists that a true counterbalancing for all positions of the door can be maintained and it is only where a true counterbalancing is maintained in all positions that minimum operating forces are effective to open and close the door. Likewise true counterbalancing in all positions is necessary to permit the door to come to a stable rest position at any point in its travel.

So as to provide a good seal between the door and jambs without excessive friction throughout the movement of the door, the pivot points 44 in the p cular doors shown are so positioned that the upper arm 38 of the door supporting yoke is t y ger than the lower arm 36. This feature is described in greater detail and claimed in my aforesaid patent No. 2,610,366, but i n t esso t al to the counterbalancing arrangements described and claimed in this divisional application. It is to be understood that our invention is not limited to the particular details shown and described, but includes all modifications, variations, and equivalents coming within the scope of the appended claims.

We claim:

1. A counterbalanced door for a building having a Wall formed substantially as a portion of a substantially horizontally disposed cylinder, and wherein the wall has an opening to form a door Way therein, said door being located within the building and behind said wall, said door being sufliciently rigid to be self-supporting and having rearwardly extending A-shaped supporting arms at opposite ends thereof, said arms having horizontal pivot points adjacent their apices whereby said door can be swung into an overhead open position about an axis established by said pivot points, a pair of counterweights, a cable attached to each counterweight, an overhead pulley for each cable, and means attaching each cable to one of said arms intermediate its apex and. said door, said means being constructed so that the total weight of the counterweights multiplied by their eifective lever arm about said pivotal axis is equal to the total weight of the door times its effective lever arm about said pivotal axis for all positions of the door.

2. A counterbalanced door for a building having a wall with an opening to form a doorway therein, said door being located within the building and behind said wall, said door being sufiiciently rigid to be self-supporting and having rearwardly extending A-shaped supporting arms at opposite ends thereof, said arms having horizontal pivot points adjacent their apices whereby said door can be swung into an overhead open position about an axis established by said pivot points, a cam-like track attached to each of said arms intermediate said door and said axis, counterweights for said door, cables attached to said counterweights, overhead pulleys for said cables, and. means attaching said cables to the ends of the cam-like tracks most remote from said pulleys, said cam-like tracks being curved so that the total weight of the counterweights multiplied by their effective lever arm about said pivotal axis is equal to the total weight of the door times its effective lever arm about said pivotal axis for all positions of the door.

3. A counterbalanced door for a building having a wall formed substantially as a portion of a substantially horizontally disposed cylinder, and wherein the wall has an opening to form a doorway therein, said door also being formed as a portion of a cylinder and being located within the building and behind said Wall, said door being sufliciently rigid to be self-supporting and having rearwardly extending A-shaped supporting arms at opposite ends thereof, said arms having horizontal pivot points adjacent their apices Whereby said door can be swung into an overhead open position about an axis established by said pivot points, a cam-like track attached to each of said arms intermediate said door and said axis, a pair of counterweights, a cable attached to each counterweight, an overhead pulley for each cable, and means attaching each cable to that end of the adjacent cam-like track most remote from its pulley, said cam-like tracks being curved so that the total weight of the counterweights multiplied by their effective lever arm about said pivotal axis is equal to the total weight of the door times its efiective lever arm about said pivotal axis for all positions of the door.

JOHN F. MCKEE. MELVIN E. HARTZLER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,214,229 Frasch Sept. 10, 1940 FOREIGN PATENTS Number Country Date 364,261 Great Britain Jan. 7, 1932 

